So I have recently ordered a ford 9" housing and axle combo for the 3rd gen project. I'm curious to know what the opinions are of the most desired width you would like to have on your cars, and why?

I like the look of deep dish wheels - but perhaps that sacrifices handle? Also requires custom wheel order in most cases

it seems if the diff was made to a 4th generation wheel width, a lot of "swappable" wheel options occur, i.e. C6 corvette wheels fit without hubs or minimal spacers.

if you've done a custom differential - what did you choose and why?

 

Narrower axle with deeper wheels is lighter, which helps handling, both because of overall weight, and because of unsprung weight. But I would choose your wheels first, 17x11s fit fairly easily, then spec the axle so you don't need spacers. Don't forget to include the thickness of the rotor hats. Anywhere from 1/4-inch to 10mm each seems common.

 

Narrower diffs also have shorter axles which will lessen the chance of twisting.

Diff width will really depend on exactly what wheel design you want to use. Since tire position under the fenders will change very little, a deep dish rim will work better with a narrow diff while a rim that's almost flush to the outside such as a corvette rim will work better with a wider diff.

 

Twisting the 31+ spline axles on 345-width, or less, drag radials? Probably not. Not at any power level. With your ultra short axleshafts, you have wrinkle-wall race slicks.